package guda.push.connect.queue;

import java.util.Collection;
import java.util.Comparator;

/**
 * Created by foodoon on 2014/12/13.
 */
public class ArrayUtil {

    public static final int MAX_ARRAY_LENGTH = Integer.MAX_VALUE - 256;

    private ArrayUtil() {} // no instance

  /*
     Begin Apache Harmony code

     Revision taken on Friday, June 12. https://svn.apache.org/repos/asf/harmony/enhanced/classlib/archive/java6/modules/luni/src/main/java/java/lang/Integer.java

   */

    /**
     * Parses the string argument as if it was an int value and returns the
     * result. Throws NumberFormatException if the string does not represent an
     * int quantity.
     *
     * @param chars a string representation of an int quantity.
     * @return int the value represented by the argument
     * @throws NumberFormatException if the argument could not be parsed as an int quantity.
     */
    public static int parseInt(char[] chars) throws NumberFormatException {
        return parseInt(chars, 0, chars.length, 10);
    }

    /**
     * Parses a char array into an int.
     * @param chars the character array
     * @param offset The offset into the array
     * @param len The length
     * @return the int
     * @throws NumberFormatException if it can't parse
     */
    public static int parseInt(char[] chars, int offset, int len) throws NumberFormatException {
        return parseInt(chars, offset, len, 10);
    }

    /**
     * Parses the string argument as if it was an int value and returns the
     * result. Throws NumberFormatException if the string does not represent an
     * int quantity. The second argument specifies the radix to use when parsing
     * the value.
     *
     * @param chars a string representation of an int quantity.
     * @param radix the base to use for conversion.
     * @return int the value represented by the argument
     * @throws NumberFormatException if the argument could not be parsed as an int quantity.
     */
    public static int parseInt(char[] chars, int offset, int len, int radix)
            throws NumberFormatException {
        if (chars == null || radix < Character.MIN_RADIX
                || radix > Character.MAX_RADIX) {
            throw new NumberFormatException();
        }
        int  i = 0;
        if (len == 0) {
            throw new NumberFormatException("chars length is 0");
        }
        boolean negative = chars[offset + i] == '-';
        if (negative && ++i == len) {
            throw new NumberFormatException("can't convert to an int");
        }
        if (negative == true){
            offset++;
            len--;
        }
        return parse(chars, offset, len, radix, negative);
    }


    private static int parse(char[] chars, int offset, int len, int radix,
                             boolean negative) throws NumberFormatException {
        int max = Integer.MIN_VALUE / radix;
        int result = 0;
        for (int i = 0; i < len; i++){
            int digit = Character.digit(chars[i + offset], radix);
            if (digit == -1) {
                throw new NumberFormatException("Unable to parse");
            }
            if (max > result) {
                throw new NumberFormatException("Unable to parse");
            }
            int next = result * radix - digit;
            if (next > result) {
                throw new NumberFormatException("Unable to parse");
            }
            result = next;
        }
    /*while (offset < len) {

    }*/
        if (!negative) {
            result = -result;
            if (result < 0) {
                throw new NumberFormatException("Unable to parse");
            }
        }
        return result;
    }


  /*

 END APACHE HARMONY CODE
  */

    /** Returns an array size >= minTargetSize, generally
     *  over-allocating exponentially to achieve amortized
     *  linear-time cost as the array grows.
     *
     *  NOTE: this was originally borrowed from Python 2.4.2
     *  listobject.c sources (attribution in LICENSE.txt), but
     *  has now been substantially changed based on
     *  discussions from java-dev thread with subject "Dynamic
     *  array reallocation algorithms", started on Jan 12
     *  2010.
     *
     * @param minTargetSize Minimum required value to be returned.
     * @param bytesPerElement Bytes used by each element of
     * the array.  See constants in {@link RamUsageEstimator}.
     *
     * @lucene.internal
     */

    public static int oversize(int minTargetSize, int bytesPerElement) {

        if (minTargetSize < 0) {
            // catch usage that accidentally overflows int
            throw new IllegalArgumentException("invalid array size " + minTargetSize);
        }

        if (minTargetSize == 0) {
            // wait until at least one element is requested
            return 0;
        }

        // asymptotic exponential growth by 1/8th, favors
        // spending a bit more CPU to not tie up too much wasted
        // RAM:
        int extra = minTargetSize >> 3;

        if (extra < 3) {
            // for very small arrays, where constant overhead of
            // realloc is presumably relatively high, we grow
            // faster
            extra = 3;
        }

        int newSize = minTargetSize + extra;

        // add 7 to allow for worst case byte alignment addition below:
        if (newSize+7 < 0) {
            // int overflowed -- return max allowed array size
            return Integer.MAX_VALUE;
        }

        if (Constants.JRE_IS_64BIT) {
            // round up to 8 byte alignment in 64bit env
            switch(bytesPerElement) {
                case 4:
                    // round up to multiple of 2
                    return (newSize + 1) & 0x7ffffffe;
                case 2:
                    // round up to multiple of 4
                    return (newSize + 3) & 0x7ffffffc;
                case 1:
                    // round up to multiple of 8
                    return (newSize + 7) & 0x7ffffff8;
                case 8:
                    // no rounding
                default:
                    // odd (invalid?) size
                    return newSize;
            }
        } else {
            // round up to 4 byte alignment in 64bit env
            switch(bytesPerElement) {
                case 2:
                    // round up to multiple of 2
                    return (newSize + 1) & 0x7ffffffe;
                case 1:
                    // round up to multiple of 4
                    return (newSize + 3) & 0x7ffffffc;
                case 4:
                case 8:
                    // no rounding
                default:
                    // odd (invalid?) size
                    return newSize;
            }
        }
    }

    public static int getShrinkSize(int currentSize, int targetSize, int bytesPerElement) {
        final int newSize = oversize(targetSize, bytesPerElement);
        // Only reallocate if we are "substantially" smaller.
        // This saves us from "running hot" (constantly making a
        // bit bigger then a bit smaller, over and over):
        if (newSize < currentSize / 2)
            return newSize;
        else
            return currentSize;
    }

    public static short[] grow(short[] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            short[] newArray = new short[oversize(minSize, RamUsageEstimator.NUM_BYTES_SHORT)];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else
            return array;
    }

    public static short[] grow(short[] array) {
        return grow(array, 1 + array.length);
    }

    public static float[] grow(float[] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            float[] newArray = new float[oversize(minSize, RamUsageEstimator.NUM_BYTES_FLOAT)];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else
            return array;
    }

    public static float[] grow(float[] array) {
        return grow(array, 1 + array.length);
    }

    public static double[] grow(double[] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            double[] newArray = new double[oversize(minSize, RamUsageEstimator.NUM_BYTES_DOUBLE)];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else
            return array;
    }

    public static double[] grow(double[] array) {
        return grow(array, 1 + array.length);
    }

    public static short[] shrink(short[] array, int targetSize) {
        assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
        final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_SHORT);
        if (newSize != array.length) {
            short[] newArray = new short[newSize];
            System.arraycopy(array, 0, newArray, 0, newSize);
            return newArray;
        } else
            return array;
    }

    public static int[] grow(int[] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            int[] newArray = new int[oversize(minSize, RamUsageEstimator.NUM_BYTES_INT)];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else
            return array;
    }

    public static int[] grow(int[] array) {
        return grow(array, 1 + array.length);
    }

    public static int[] shrink(int[] array, int targetSize) {
        assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
        final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_INT);
        if (newSize != array.length) {
            int[] newArray = new int[newSize];
            System.arraycopy(array, 0, newArray, 0, newSize);
            return newArray;
        } else
            return array;
    }

    public static long[] grow(long[] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            long[] newArray = new long[oversize(minSize, RamUsageEstimator.NUM_BYTES_LONG)];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else
            return array;
    }

    public static long[] grow(long[] array) {
        return grow(array, 1 + array.length);
    }

    public static long[] shrink(long[] array, int targetSize) {
        assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
        final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_LONG);
        if (newSize != array.length) {
            long[] newArray = new long[newSize];
            System.arraycopy(array, 0, newArray, 0, newSize);
            return newArray;
        } else
            return array;
    }

    public static byte[] grow(byte[] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            byte[] newArray = new byte[oversize(minSize, 1)];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else
            return array;
    }

    public static byte[] grow(byte[] array) {
        return grow(array, 1 + array.length);
    }

    public static byte[] shrink(byte[] array, int targetSize) {
        assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
        final int newSize = getShrinkSize(array.length, targetSize, 1);
        if (newSize != array.length) {
            byte[] newArray = new byte[newSize];
            System.arraycopy(array, 0, newArray, 0, newSize);
            return newArray;
        } else
            return array;
    }

    public static boolean[] grow(boolean[] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            boolean[] newArray = new boolean[oversize(minSize, 1)];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else
            return array;
    }

    public static boolean[] grow(boolean[] array) {
        return grow(array, 1 + array.length);
    }

    public static boolean[] shrink(boolean[] array, int targetSize) {
        assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
        final int newSize = getShrinkSize(array.length, targetSize, 1);
        if (newSize != array.length) {
            boolean[] newArray = new boolean[newSize];
            System.arraycopy(array, 0, newArray, 0, newSize);
            return newArray;
        } else
            return array;
    }

    public static char[] grow(char[] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            char[] newArray = new char[oversize(minSize, RamUsageEstimator.NUM_BYTES_CHAR)];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else
            return array;
    }

    public static char[] grow(char[] array) {
        return grow(array, 1 + array.length);
    }

    public static char[] shrink(char[] array, int targetSize) {
        assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
        final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_CHAR);
        if (newSize != array.length) {
            char[] newArray = new char[newSize];
            System.arraycopy(array, 0, newArray, 0, newSize);
            return newArray;
        } else
            return array;
    }

    public static int[][] grow(int[][] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            int[][] newArray = new int[oversize(minSize, RamUsageEstimator.NUM_BYTES_OBJECT_REF)][];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else {
            return array;
        }
    }

    public static int[][] grow(int[][] array) {
        return grow(array, 1 + array.length);
    }

    public static int[][] shrink(int[][] array, int targetSize) {
        assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
        final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_OBJECT_REF);
        if (newSize != array.length) {
            int[][] newArray = new int[newSize][];
            System.arraycopy(array, 0, newArray, 0, newSize);
            return newArray;
        } else {
            return array;
        }
    }

    public static float[][] grow(float[][] array, int minSize) {
        assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
        if (array.length < minSize) {
            float[][] newArray = new float[oversize(minSize, RamUsageEstimator.NUM_BYTES_OBJECT_REF)][];
            System.arraycopy(array, 0, newArray, 0, array.length);
            return newArray;
        } else {
            return array;
        }
    }

    public static float[][] grow(float[][] array) {
        return grow(array, 1 + array.length);
    }

    public static float[][] shrink(float[][] array, int targetSize) {
        assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
        final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_OBJECT_REF);
        if (newSize != array.length) {
            float[][] newArray = new float[newSize][];
            System.arraycopy(array, 0, newArray, 0, newSize);
            return newArray;
        } else {
            return array;
        }
    }

    /**
     * Returns hash of chars in range start (inclusive) to
     * end (inclusive)
     */
    public static int hashCode(char[] array, int start, int end) {
        int code = 0;
        for (int i = end - 1; i >= start; i--)
            code = code * 31 + array[i];
        return code;
    }

    /**
     * Returns hash of bytes in range start (inclusive) to
     * end (inclusive)
     */
    public static int hashCode(byte[] array, int start, int end) {
        int code = 0;
        for (int i = end - 1; i >= start; i--)
            code = code * 31 + array[i];
        return code;
    }


    // Since Arrays.equals doesn't implement offsets for equals
    /**
     * See if two array slices are the same.
     *
     * @param left        The left array to compare
     * @param offsetLeft  The offset into the array.  Must be positive
     * @param right       The right array to compare
     * @param offsetRight the offset into the right array.  Must be positive
     * @param length      The length of the section of the array to compare
     * @return true if the two arrays, starting at their respective offsets, are equal
     *
     * @see java.util.Arrays#equals(char[], char[])
     */
    public static boolean equals(char[] left, int offsetLeft, char[] right, int offsetRight, int length) {
        if ((offsetLeft + length <= left.length) && (offsetRight + length <= right.length)) {
            for (int i = 0; i < length; i++) {
                if (left[offsetLeft + i] != right[offsetRight + i]) {
                    return false;
                }

            }
            return true;
        }
        return false;
    }

    // Since Arrays.equals doesn't implement offsets for equals
    /**
     * See if two array slices are the same.
     *
     * @param left        The left array to compare
     * @param offsetLeft  The offset into the array.  Must be positive
     * @param right       The right array to compare
     * @param offsetRight the offset into the right array.  Must be positive
     * @param length      The length of the section of the array to compare
     * @return true if the two arrays, starting at their respective offsets, are equal
     *
     * @see java.util.Arrays#equals(byte[], byte[])
     */
    public static boolean equals(byte[] left, int offsetLeft, byte[] right, int offsetRight, int length) {
        if ((offsetLeft + length <= left.length) && (offsetRight + length <= right.length)) {
            for (int i = 0; i < length; i++) {
                if (left[offsetLeft + i] != right[offsetRight + i]) {
                    return false;
                }

            }
            return true;
        }
        return false;
    }

  /* DISABLE THIS FOR NOW: This has performance problems until Java creates intrinsics for Class#getComponentType() and Array.newInstance()
  public static <T> T[] grow(T[] array, int minSize) {
    assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
    if (array.length < minSize) {
      @SuppressWarnings("unchecked") final T[] newArray =
        (T[]) Array.newInstance(array.getClass().getComponentType(), oversize(minSize, RamUsageEstimator.NUM_BYTES_OBJECT_REF));
      System.arraycopy(array, 0, newArray, 0, array.length);
      return newArray;
    } else
      return array;
  }

  public static <T> T[] grow(T[] array) {
    return grow(array, 1 + array.length);
  }

  public static <T> T[] shrink(T[] array, int targetSize) {
    assert targetSize >= 0: "size must be positive (got " + targetSize + "): likely integer overflow?";
    final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_OBJECT_REF);
    if (newSize != array.length) {
      @SuppressWarnings("unchecked") final T[] newArray =
        (T[]) Array.newInstance(array.getClass().getComponentType(), newSize);
      System.arraycopy(array, 0, newArray, 0, newSize);
      return newArray;
    } else
      return array;
  }
  */

    // Since Arrays.equals doesn't implement offsets for equals
    /**
     * See if two array slices are the same.
     *
     * @param left        The left array to compare
     * @param offsetLeft  The offset into the array.  Must be positive
     * @param right       The right array to compare
     * @param offsetRight the offset into the right array.  Must be positive
     * @param length      The length of the section of the array to compare
     * @return true if the two arrays, starting at their respective offsets, are equal
     *
     * @see java.util.Arrays#equals(char[], char[])
     */
    public static boolean equals(int[] left, int offsetLeft, int[] right, int offsetRight, int length) {
        if ((offsetLeft + length <= left.length) && (offsetRight + length <= right.length)) {
            for (int i = 0; i < length; i++) {
                if (left[offsetLeft + i] != right[offsetRight + i]) {
                    return false;
                }

            }
            return true;
        }
        return false;
    }

    public static int[] toIntArray(Collection<Integer> ints) {

        final int[] result = new int[ints.size()];
        int upto = 0;
        for(int v : ints) {
            result[upto++] = v;
        }

        // paranoia:
        assert upto == result.length;

        return result;
    }

    private static class NaturalComparator<T extends Comparable<? super T>> implements Comparator<T> {
        NaturalComparator() {}
        @Override
        public int compare(T o1, T o2) {
            return o1.compareTo(o2);
        }
    }

    @SuppressWarnings("rawtypes")
    private static final Comparator<?> NATURAL_COMPARATOR = new NaturalComparator();

    /** Get the natural {@link Comparator} for the provided object class. */
    @SuppressWarnings("unchecked")
    public static <T extends Comparable<? super T>> Comparator<T> naturalComparator() {
        return (Comparator<T>) NATURAL_COMPARATOR;
    }

    /** Swap values stored in slots <code>i</code> and <code>j</code> */
    public static <T> void swap(T[] arr, int i, int j) {
        final T tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }

    // intro-sorts







}
